The field of this invention is "oral compositions" which term is used herein to designate products which in the ordinary course of usage are retained in the oral cavity for a time and in a manner sufficient to contact essentially all of the dental surfaces, but are not intentionally ingested. Such products include, for example, dentifrices, mouthwashes, prophylaxis pastes and topical solutions.
The bis-biguanide compounds of this invention are known, having been disclosed in U.S. Pat. No. 2,684,924, Rose et al., patented July 27, 1954; U.S. Pat. No. 2,990,425, Senior et al., patented June 27, 1961; U.S. Pat. No. 2,830,006, Burtwell et al, patented Apr. 8, 1958; U.S. Pat. No. 2,863,919, Burtwell et al., patented Dec. 9, 1958, and Kemanord; Netherlands application 72/06762, published Nov. 21, 1972 (Corresponds to British Pat. No. 1,381,361, published Jan. 22, 1975).
Attempts have been made in the prior art to reduce the tooth-staining tendency of bis-biguanide antiplaque agents. For example Haefele, U.S. Pat. No. 3,934,002 issued Jan. 20, 1976 and Haefele's pending U.S. pat. application Ser. No. 635,030, filed Nov. 25, 1975, relate to the formation of insoluble bis-biguanide salts to reduce staining of teeth. Such insoluble materials are not, however, very useful in formulating clear liquid oral products such as mouthwashes and gel toothpastes.
It is also possible to reduce the tooth staining tendency of bis-biguanides by combining them with metal chelating agents. For example, Haefele, U.S. Pat. No. 3,937,807, issued Feb. 10, 1976 discloses the combination of bis-biguanides with certain amino carboxylate compounds. Furthermore, our concurrently filed copending application having Ser. No. 681,868 (continuation-in-part of Ser. No. 652,692, filed Jan. 27, 1976 and its parent applications) disclose that particular chelating agents are effective in reducing staining by the bis-biguanides, without the formation of insoluable salts. Care must be taken, however, in selecting chelating agents for use in oral compositions since some chelators have a tendency to damage dental enamel. There is thus a continuing need for reduced staining bis-biguanide compositions which contain soluble materials and which do not contain chelating agents that are potentially damaging to teeth.
Accordingly, it is an object of the present invention to provide antiplaque compositions and methods which employ bis-biguanides but which produce little or no stain on dental surfaces.
It is a further object of the present invention to provide reduced staining anti-plaque compositions and methods which utilize water soluble materials.
It is a further object of the present invention to provide reduced staining antiplaque compositions and methods which employ materials that are chemically compatible with dental enamel.
It has been discovered that by combining bisbiguanide antiplaque agents and chelating agents such as ethylenediamine diacetic acids and salts, the above objectives can be realized and reduced staining, antiplaque compositions and methods can be provided which are unexpectedly superior to similar compositions and methods of the prior art.